Alzheimer’s disease (AD) is the most common form of dementia
characterized clinically with progressive cognitive decline and neuronal loss.
Pathologically, AD affected brain shows accumulation of β-amyloid (Aβ) plaques
and neurofibrillary tangles formed by the hyper phosphorylation of tau protein.
Recent studies indicate that mitochondrial dysfunction, a pathological featurethat can be detected early in AD. Nitric oxide synthases (NOS) are a family of
enzymes catalyzing the production of nitric oxide (NO), which functions as neuronal
signalingmolecule. Altered expression of nNOS by the Aβ stimulus
results in the formation of peroxy nitrite and reactive oxygen species. These
peroxy-nitrite, nitrosylates the cytoplasmic protein tau and phosphorylates
GSK-3β.
Nitrosylation of tau protein results in structural and
conformational change of tau protein ensuring the destabilization of
microtubule. This leads to dissociation of tau protein from microtubule and
oligomerization of tau occurs to form neuro-fibrillary tangles (NFT’s). These
tangles forms a physical road blocks within the neuronal cells and interrupts
the neurotransmitter signaling.
GBM, a grade IV glioma classified by World Health
Organization, is considered highly malignant, vascular and invasive subtype.
Hypoxia and neovascularization are signature histopathologic features of GBM,
which is most lethal during first year after initial diagnosis despite surgical
resection and other standard therapies. Temozolomide chemotherapy andradiotherapy against GBM tumor cells have led to a significant improvement intumor growth and patient survival in newly diagnosed and recurrent GBM. The
survival advantage conferred by temozolomide chemotherapy is associated with
methylation of the promoter region of the gene encoding O6-methylguanine
DNAmethyltransferase (MGMT). Both tumor protein p53 (TP53) and MGMT are
involved in DNA repair after chemotherapy or radiotherapy, which may contribute
to drug resistance. In addition, tumor cells acquiring several mutations during
tumor progression could contribute to therapy resistance in GBM.
Increased productivity is one of the most important
objectives in continuous production of ethanol. It is generally accepted that a
high concentration of yeast favors an increased ethanol yield of the
fermentation process . Several techniques that promote the accumulation ofbiomass in fermenters have been used in continuous fermentation processes,
including cell immobilization in polymeric matrices and cell recycle by
centrifugation or filtration through membranes. Good performances have been
reported for processes using immobilized cells; however, procedures and
materials involved in this technique are inaccessible to a large number of
small industrial units . Centrifugation and filtration equipments are extremely
expensive and prone to mechanical problems; the use of these equipments is
limited due to high investment and maintenance costs. Since yeast separation by
conventional methods is an expensive operation in alcoholic fermentation
plants, alternative separation techniques using cheaper equipment such as
hydrocyclones and settlers have been investigated aiming to reduce the costs
involved in ethanol production.
Although solid particles can settle under the action of a
centrifugal force, gravitational sedimentation is understood as the settling of
particles within a fluid under the force of gravity. The factors that controlthe settling velocity are the solids concentration in the slurry, the densities
of solid and liquid, the size and shape of the particles and the viscosity of
the medium. However, the most important factors are the particle size and
particle density.
Jasmonic acid (JA) is one of the most signaling
phytohormones which play an essential role in plant development and response to
biotic and abiotic stresses. It plays a key regulatory role in root elongation,
pollen production, germination, fruit ripening, plant senescence. Additionally,
it activates plant defenses against pests, pathogens and abiotic stress.
Jasmonic acid and its derivative methyl jasmonate are abundant in plant cellsand have a physiological signaling mechanism. Recently, jasmonates have been
reported to be the active forms precursors comprising certain amino acid conjugates.
Jasmonates are generally synthesized and accumulated upon environmental or
developmental stimuli. Jasmonate signal transduction process is regulated by a
signaling mechanism embracing certain repressor proteins which control
different transcription factors regulating the expression of jasmonate
responsive genes.
The first step of JA synthesis takes place in
chloroplasts membranes, where a phospholipase generates both of α-linolenic
acid and hexadecatrienoic acid from membrane phospholipids. JAs synthesisoccurs generally from the α-linolenic acid precursor through the octadecanoidpathway. Chloroplastic 13-lipoxygenase oxidizes αLA forming the 13-hydroperoxy
derivative of linolenic acid. The Arabidopsis genome comprises six genes
encoding lipoxygenases. Three of such genes (LOX2, LOX3 and LOX4) regulate JA
production. The next steps of JA synthesis occur in the peroxisome.
Progesterone is considered as the pregnancy hormone.
Already in 1958 Short was able to determine progesterone in blood and found
that during pregnancy its levels increase from <0.1 μg/100 mL (nonpregnant)
up to 87 μg/100 ml. In addition, Eton and Short found that in early abortion or
premature delivery the concentration of progesterone was relatively low, which
finding were confirmed by Wiest for fetal death. The role of progesteroneduring pregnancy includes the preparation of the uterus for implantation, to
keep the uterus quiescent during gestation and lower immune responses of the
mother. Initially, it is produced by the corpus luteum and after about 8 weeks
by the placenta. It is suggested that a decline in progesterone levels
facilitate the onset of labor and triggers milk production. Premature labour is
characterized by progesterone concentrations lower than normal and may be
prevented by the administration of progesterone, 17OHprogesterone or
17-hydroxyprogesterone-caproate. An update of this subject was given in a
lecture during 14th Annual Symposium at the University of Illinois, Chicago, by
Grobman, October 31, 2014.
The drop in progesterone levels as a trigger to the onset
of labor has been assessed in sheep and other mammals and called‘P-withdrawal’. Attempts to confirm this mechanism in humans has been hampered
by the fact that repeated blood sampling is too stressful and not feasible in
situations that there is no health threat or medical indication.
